The invention concerns a method for controlling a power-shift, multi-speed boat transmission.
Multi-speed boat transmission, combined with a fixed propeller or water jet, are know already. Such transmissions allow a variable adaptation of the motor to different operating conditions whereby the motor can always work at the optimum rotational speed range.
DE 196 24 913 A1 discloses a marine transmission system having one motor, one shifting mechanism and one programmable electronic control device with a shift parameter matrix. The electronic control device monitors the motor load and the rate of revolutions and produces a control signal which controls the shifting operations.
DE 19 49 938 has made known a shifting automatic system for a boat transmission system having one-step or multi-step transmissions wherein a first control loop adjusts, via the torque of the boat propeller, the output rotational speed of the transmission required by the driving conditions that occur and a second control loop controls the rotational speed of the motor and the output of the motor in accordance with the first control loop.
The above cited prior art requires coordination of the transmission with the electronic system of the motor. Consequently, it is not possible to combine different types of transmission with different motors without high expenditure in adaptation and costs.
The invention is based on the problem of making available a method for control of a power-shift, multi-speed transmission which automatically permits a variable adaptation to different operating conditions without requiring a coordination of the transmission with the electronic system of the motor.
Thereby the inventive method can be universally utilizable.
In addition, the change of gear must occur without traction interruption. This is of great importance, particularly in fast boats, in order that during the gearshift operation the boat does not fall off the plane with its low resistance to the motion.
Accordingly, it is proposed to deduce the intended acceleration from the movement of the control lever or from the change of the input rotational speed of the transmission and thus to introduce a shifting operation at different rotational speeds of the motor.
Consequently, a quick movement of the control lever or a quick upshift of the motor is interpreted as a desire for high acceleration for the boat and the shift point in the higher gear is moved toward high motor rotational speeds. In such a case, the rotational speed of the motor at the shift point can amount to 95% of the nominal rotational speed and preferably be in the interval between 80% and 100% of the nominal rotational speed.
On the other hand, a slow movement of the control lever or a slow upshift of the motor is interpreted as a desire for a more moderate acceleration of the boat and the shift point in the high gear is moved toward low rotational speeds of the motor. A typical value of the rotational speed of the motor at the shift point is 75% of the nominal rotational speed. Other values for the rotational speed of the motor at the shift point can be in the interval between 60% and 80% of the nominal rotational speed value.
According to the invention, the upshift is introduced only when the forward gear is engaged. For reasons of safety, the quick gear cannot be engaged in reverse motion.
According to the invention, the possibility of a kick-down downshift is provided for when it should be accelerated at a rotational speed range above the rotational speed of the downshift.
In boats equipped with a multi-engine installation, the shifting operation occurs simultaneously in all transmissions as soon as a transmission meets the shifting criterion.
The rotational speed of the motor can be optionally lowered during the gear shift.
This described method also provides for the possibility of a manual gear shift. However, to prevent damage to the power transmission due to operating error, the rotational speed range for manual gear shift is limited, a typical value of the nominal rotational speed being 45% here. At high rotational speeds of the motor, the introduced gear position is blocked.
The inventive control method has the advantage that an expensive coordination with the electronic system of the motor is not required. Thus, several types of transmissions can be combined with several motors.